The problem is to present access to your device (pc, raspberry etc) which has usb-dongle (or wifi) connected to mobile internet provider. So, in this case you have no public (white) IP address and this is the challenge! The solution i advice is to use SSH tunnel. For this you need public SSH server accessible read more »

To change the default password for SYS and SYSTEM users use the trick. 1. Run in shell: sqlplus / as sysdba 2. Change password for SYS: SQL> alter user SYS identified by “your-super-password”; 3. Change password for SYSTEM: SQL> alter user SYSTEM identified by “your-super-password”; Thanx to http://stackoverflow.com/a/740884

To generate SSH key you have to do following: 1. Install any SSH client (if absent). 2. Show existing keys: ls -la ~/.ssh It can be empty. 3. Generate key itself: ssh-keygen -t rsa -b 4096 -C “your@email.com” You’ll be prompted to enter the path to store the key. Also, you can enter a passphrase. read more »

If you are using, for example GIT, it may be needed to use different ssh keys for different servers. By default git client uses “~/.ssh/id_rsa” private key. And you’ll get the error like: Permission denied (publickey). fatal: Could not read from remote repository. Please make sure you have the correct access rights and the repository read more »